Control unit and method for producing the same

ABSTRACT

The present invention relates to a control unit ( 1 ), for automotive applications in particular, with: a frame ( 8 ) that includes a recess ( 9 ) across which electrical conductive tracks ( 10 ) extend to supply electrical power; a base plate ( 11 ) that is inserted in the frame ( 8 ); a circuit carrier ( 12 ) on which electronic components are mounted and which is installed on the base plate ( 11 ); an electrical connection ( 14 ) for connecting the circuit carrier ( 12 ) with the conductive tracks ( 10 ); and a cover ( 4 ) for hermetically sealing the control unit ( 1 ), the cover including a shaped section that is insertable in the associated recess ( 9 ) in the frame ( 8 ); whereby a sealing gel ( 16 ) is provided in recess ( 9 ) with a viscosity such that the sealing gel ( 16 ) can flow around the electrical conductive tracks ( 10 ) that extend across the recess ( 9 ). The present invention further relates to a manufacturing method for manufacturing a control unit ( 1 ) of this type.

BACKGROUND INFORMATION

The present invention relates to a control unit, for automotiveapplications in particular, according to the definition of the speciesin Claim 1, and a method for manufacturing the control unit.

In automotive applications in particular, control units are subjected tostrong mechanical loads due to vibratory stresses.

Control units are used in automotive applications for transmission-shiftcontrol, for example. A control unit according to the related art isdescribed below with reference to FIGS. 1 and 2. FIG. 1 shows anunderside view of a conventional control unit, and FIG. 2 shows alateral cross-sectional view of the conventional control unit along theline A-A in FIG. 1.

Control unit 1 contains, for example, a hybrid control unit 2, sensorsand at least one plug-in connector for connection to a vehicle wiringharness and/or a transmission connector. The electrical connectionbetween hybrid control unit 2, the sensors and the transmissionconnector is established via a pressed screen 3. Control unit 1 includesa cover 4 designed to ensure that control unit 1 is closed. Furthermore,the electronic circuit is provided on hybrid control unit 2 in thehousing. Glass-enclosed pins 5 are located on the underside of controlunit 1 to establish electrical contact between the electronic circuitand pressed screen 3, the pins being mounted on a pin strip 6. Theelectrical contact of the circuit carrier with glass-enclosed pins 5 isestablished via bonding, and glass-enclosed pins 5 are contacted withpressed screen 3 using laser welding.

Control unit housings are used in various applications, e.g., in ABSsystems, in the case of which the conductive tracks are injected in aplastic housing in which the electronic circuit is located, to establishcontact with the circuit. The housing is closed with a cover 4 in aconventional manner, the cover being either bonded to the carrier of thecontrol unit or cast therein.

A disadvantage of the known procedure described above is the fact thatthe conductive tracks injected in the plastic cannot be sealedcompletely.

Various proposals for improving the seal between the conductive tracksand the plastic are found in the related art. For example, theconductive tracks are pressed into the plastic in the form of pins,whereby the pins must have an exactly defined, highly precise shape.

According to a further proposal, each conductive track is enclosed in aplastic material that is designed to perform the sealing function.

Both means of achieving the object of the inventions have thedisadvantage, however, that they can be realized technically and areeconomically practical only when a few connecting lines and/orconductive tracks are required and the distances between the connectionsand/or conductive tracks are relatively great.

ADVANTAGES OF THE INVENTION

Compared to the known means of achieving the object of the inventions,the control unit according to the present invention having the featuresof Claim 1, and the corresponding procedure for manufacturing the same,according to Claim 8, have the advantage that a control unit is createdthat is completely hermetically sealed while ensuring that the circuitlocated in the housing is contacted to the outside in a simple manner,whereby a large number of contacts can be easily provided.

Furthermore, the contacts can have a small grid pattern, which reducesthe amount of installation space required, and they can be locatedrelatively at random. In addition, the control unit according to thepresent invention can be manufactured in a simple and, therefore,economical manner.

According to the idea on which the present invention is based, a sealinggel is provided in a recess in the frame of the control unit, thesealing gel having a viscosity such that it can flow around theelectrical conductive tracks that pass through the recess and around ashaped section of a cover that is inserted in the recess.

It is therefore ensured by way of a single seal that each conductivetrack is sealed individually and a seal is provided between the baseplate and the cover of the control unit. The geometric configuration ofthe individual conductive tracks is inconsequential, so that when apressed screen is used for the conductive tracks, for example, folds,constrictions, etc. on the punched edges do not affect the sealingbehavior. Furthermore, no particular geometric accuracy of theconductive tracks and/or the grid pattern between the conductive tracksis required. Simple, economical manufacture is therefore possible.

Since the conductive tracks can be present in any number and in anypattern of distribution on and/or in the housing frame, it is easier toadapt to the requirements of the circuit layout and/or the surroundingstructural conditions.

In addition to the circuit carrier, further electronic components can beprovided in the housing and contacted with the circuit carrier and/or tothe outside. Expensive installation space in the control unit and/or onthe circuit carrier can therefore be spared. Components that cannot belocated on the circuit carrier, for example, such as large capacitors orcomponents having high electromagnetic radiation or power loss, canstill be contacted with the circuit carrier in a simple manner.

Advantageous further developments and improvements of the control unitdescribed in Claim 1 and of the method for manufacturing the samedescribed in Claim 8 are provided in the subclaims.

According to a preferred further development, the sealing gel isdesigned as silicone gel that retains its elastic properties after apossible hardening procedure.

According to another preferred further development, the shaped sectionon the cover includes as least one receiving area for receiving acertain amount of the sealing gel when the control unit is in apressed-in state. When force is applied, the sealing gel can thereforeenter the receiving area of the shaped section and ensure a better seal.

The recess in the frame is preferably configured as a circumferentialgroove. Accordingly, the shaped section of the cover is preferablyconfigured as the spring associated with the groove, the spring alsohaving a circumferential configuration.

The cover is preferably joinable with the frame using laser welding, asnap-in connection, a shaped spring device or the like. The preferredconnecting means can be selected in accordance with the application ofthe control unit and/or the site of application of the control unit.

The base plate is composed, particularly advantageously, of a materialhaving good thermal conductivity, e.g., metal. Good heat dissipation toa cooling surface connected with the base plate is therefore ensured.

The conductive tracks are configured as pressed-screen conductive tracksor as flexible-foil conductive tracks in particular. Anotherconfiguration of the conductive track is also feasible, however, sincethe viscous sealing gel can flow around any geometric shape.

According to another preferred further development, the control unit ispressed onto the associated surface by way of a spring device. Thissurface can be the carrier surface of a transmission housing or acooling surface having a different configuration. This application offorce creates hydrostatic pressure in the sealing gel, which markedlyimproves the sealing property. Furthermore, the entire structure of thecontrol unit is held together by the action of force.

DRAWING

Exemplary embodiments of the present invention are shown in the drawingand are described in greater detail in the description below.

FIG. 1 shows an underside view of a control unit according to therelated art;

FIG. 2 shows a lateral cross-sectional view of the control unit in FIG.1 along the line A-A;

FIG. 3 shows a top view of a control unit according to a first exemplaryembodiment of the present invention with the cover removed;

FIG. 4 shows a section of a lateral cross-sectional view of a controlunit according to a second exemplary embodiment of the presentinvention;

FIG. 5 shows a section of a lateral cross-sectional view of a controlunit according to a third exemplary embodiment of the present invention;

FIG. 6 shows a section of a lateral cross-sectional view of a controlunit according to a fourth exemplary embodiment of the presentinvention;

FIG. 7 shows a perspective view of the shaped spring device in FIG. 6;

FIG. 8 shows a section of a lateral cross-sectional view of a controlunit according to a fifth exemplary embodiment of the present inventionin a first state;

FIG. 9 shows a section of a lateral cross-sectional view of a controlunit according to a fifth exemplary embodiment of the present inventionin a second state;

FIG. 10 shows a section of a lateral cross-sectional view of a controlunit according to a sixth exemplary embodiment of the present invention;

FIG. 11 shows a top view of a control unit according to a seventhexemplary embodiment of the present invention with the cover removed;and

FIG. 12 shows a top view of a control unit according to an eighthexemplary embodiment of the present invention with the cover removed.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENT

In the figures, the same reference numerals are used to label componentsthat are the same or that perform the same function.

FIG. 3 shows a top view of a control unit 1 with the cover removedaccording to a first exemplary embodiment of the present invention.Control unit 1 includes a frame 8 that is preferably made of plastic andincludes a circumferential groove 9.

Conductive tracks 10 are preferably injected into plastic frame 8 andextend through groove 9. Conductive tracks 10 can be configured aspressed-screen conductive tracks or as flexible-foil conductive tracks.

Control unit 1 further includes a base plate 11 that is preferably madeof a material with good heat-conducting properties. Base plate 11 can bemade of metal, for example. A circuit carrier 12, e.g., an LTCC or ahybrid, is located on base plate 11, the circuit carrier being equippedwith electronic components 13. Circuit carrier 12 is contactedelectrically with conductive tracks 10 preferably via a bond connection14.

Control unit 1 is furthermore closed with a cover (not shown in FIG. 3),whereby a sealing gel is filled between the cover, frame 8 and baseplate 11. This is described in greater detail below in the descriptionof the further figures.

FIG. 4 shows a partial section of a lateral cross-sectional view of acontrol unit 1 according to a second exemplary embodiment of the presentinvention. As shown in FIG. 4, conductive tracks 10 extend throughcircumferential groove 9 provided in frame 8. A sealing gel 16, whichwill be described in detail below, is filled into groove 9. Cover 4includes a spring and/or shaped section 40 associated with groove 9, thespring and/or shaped section also preferably having a circumferentialconfiguration. Shaped section 40 is configured as a spring such that itis insertable in associated groove 9 in a form-locked manner when cover4 is placed on frame 8. For example, shaped section 40 of cover 4 has ashape on its free end that corresponds to two sealing lips; thisprovides additional protection against sealing gel 16 seeping betweenframe 8 and cover 4.

The individual method steps for manufacturing control unit 1 areexplained below as examples. First, base plate 11 is pressed and/orglued into frame 8.

Circuit carrier 12 is then glued to base plate 11, and electroniccomponents (not shown) are mounted on it. Electronic components can alsobe applied before circuit carrier 12 is mounted on base plate 11.

Contact is then established between circuit carrier 12 and conductivetracks 10, whereby a bond connection 14 is preferably used for a contactof this type.

A sealing gel 16 is then poured into circumferential groove 9 of frame8, whereby sealing gel 16 has a viscosity such that sealing gel 16 flowsaround conductive tracks 10 that extend through groove 9. Sealing gel 16is preferably made of a material that retains its elastic propertiesafter a possible hardening procedure. Sealing gel 16 is composed ofsilicone, for example.

Cover 4, which is also preferably a plastic injection-molded part, isthen inserted into groove 9 of frame 8 via its shaped section 40 and ispreferably acted upon with a predetermined amount of force F in thedirection of the arrow shown in FIG. 4 such that hydrostatic pressurebuilds in the sealing gel, which is the pressure required to seal thearrangement.

A plurality of variations is imaginable for applying force F to cover 4.According to the second exemplary embodiment of the present invention,as shown in FIG. 4, cover 4 can be joined with frame 8 using alaser-welded joint 17. For this purpose, cover 4 includes an edgesection 41, the inner surface of which bears against an exterior surfaceof frame 8 and is the preferred welding location.

FIG. 5 shows a section of a lateral cross-sectional view of a controlunit 1 according to a third exemplary embodiment of the presentinvention. Edge section 41 of cover 4 includes lock-in projections 42that can preferably engage in multiple stacked notches 80 in the surfaceof frame 8 associated with edge section 41.

FIG. 6 shows a partial section of a lateral cross-sectional view of acontrol unit 1 according to a fourth exemplary embodiment of the presentinvention. Force F is applied by a shaped spring device 18 that isconfigured, for example, as shown in FIG. 8 in a perspective view.Shaped spring device 18 is composed preferably of metal and ispretensioned in the direction of the longitudinal axis of shaped springdevice 18. Shaped spring device 18 includes a pair of shorter snap-inhooks 180 and a pair of longer snap-in hooks 181. In the installedstate, shorter snap-in hooks 180, for example, are engaged with aprojection 110 on base plate 11, and longer snap-in hooks 181 bearagainst the top surface of cover 4. As a result, cover 4 is pressed bymetallic shaped spring device 18 in the direction of base plate 11 witha predetermined amount of force F. The shape required for lateralfixation of shaped spring device 18 on base plate 11 is advantageouslycreated by extruding base plate 11.

FIGS. 8 and 9 show a partial section of a lateral cross-sectional viewof a control device 1 according to a fifth exemplary embodiment of thepresent invention in a first and second state.

In FIG. 8, shaped section 40 and/or spring 40 of cover 4 is inserted ingroove 9 such that the front side of shaped section 40 comes in contactwith sealing gel 16. According to this exemplary embodiment, shapedsection 40 includes at least one receiving region 43 that is preferablyconfigured as a circumferential material recess, by way of whichhydrostatic pressure is created in sealing gel 16 when force F isapplied to cover 4 in the direction of the arrow in FIG. 9 and a portionof sealing gel 16 is pressed into the volume formed by recesses 43, asshown in FIG. 9. An improved seal of the arrangement can be achieved asa result.

FIG. 10 shows a lateral cross-sectional view of control unit 1 accordingto a sixth exemplary embodiment of the present invention. Since controlunit 1 is designed to be used in an automatic transmission forautomotive applications—in which extremely high operating temperaturesexist—contact cooling for control unit 1 is advantageous. For thisreason, control unit 1 with the preferably metallic base plate 11 can bemounted on a cooling surface 19 in a transmission housing, for example.A spring device 20 is provided to apply the contact pressure, the springdevice pressing cover 4 onto base plate 11, by way of which sealing gel16 is located in the flow of force of spring device 20. Furthermore, acomplex manner of affixing base plate 11 in frame 8 can also beeliminated as a result.

FIG. 11 shows a top view of a control unit 1 according to a seventhexemplary embodiment of the present invention, without the cover inplace. It is clear that control unit 1 can have any shape that isadvantageous to enable the necessary electronic components and circuitsto be placed in the interior region. The cover and its associated shapedsection are shaped in accordance with the particular groove such that aform-locked insertion of the cover into groove 9 is ensured.

Furthermore, by way of a certain spacial configuration of control unit1, it is possible to house further electronic components 15 in additionto the circuit carrier in the housing, as shown in FIG. 11, and tocontact them with the circuit carrier or toward the outside. Anadditional advantage can be obtained as a result, since expensivesurface area on the circuit carrier can be spared and components can beused that cannot be built on the circuit carrier due to their dimensionsor their excessive electromagnetic radiation and/or power losses.

FIG. 12 shows a top view of a control unit 1 with the cover removed,according to an eighth exemplary embodiment of the present invention. Itis obvious to one skilled in the art that conductive tracks 10 can belocated on only one side or on a plurality of sides of frame 8, inaccordance with the particular application.

Although the present invention was described above with reference topreferred exemplary embodiments, it is not limited to them and, instead,can be modified in a diverse manner.

The present invention therefore creates a control unit and a method formanufacturing the same, the method providing a hermetic seal for theinterior space in which the circuit carriers and associated electroniccomponents are located. The control unit is configured such thatindividualized sealing is ensured for each conductive track and a sealagainst the base plate and cover is ensured by way of a single seal,namely via the sealing gel. As a result, the exact geometricconfiguration of the individual conductive tracks is inconsequential,i.e., folds, constrictions, etc. on the punched edges are notsignificant, since the sealing gel, with its predetermined viscosity,flows around the conductive tracks having any shape. Simple, economicalmanufacture of a hermetically sealed control unit is therefore possible.

The number and distribution of the individual conductive tracks on thehousing frame can therefore be configured in any possible manner,enabling easy adaptation to the specification of the circuit layoutand/or surrounding structural conditions.

1. A control unit (1), for automotive applications in particular, with:a frame (8) that includes a recess (9) across which electricalconductive tracks (10) extend to supply electrical power; a base plate(11) that is inserted in the frame (8); a circuit carrier (12) on whichelectronic components are mounted and which is installed on the baseplate (11); an electrical connection (14) for connecting the circuitcarrier (12) with the conductive tracks (10); and with a cover (4) forhermetically sealing the control unit (1), the cover including a shapedsection that is insertable in the associated recess (9) in the frame(8); wherein a sealing gel (16) is provided in recess (9) with aviscosity such that the sealing gel (16) can flow around the electricalconductive tracks (10) that extend across the recess (9).
 2. The controlunit as recited in claim 1, wherein the sealing gel (16) is designed assilicone gel, which remains elastic after a possible hardeningprocedure.
 3. The control unit as recited in claim 1, wherein the shapedsection (40) of the cover (4) includes at least one receiving area (43)for receiving sealing gel in a pressed-together state.
 4. The controlunit as recited in claim 1, wherein the recess (9) of the frame (4) isconfigured as a circumferential groove (9), and the shaped section (40)of the cover (4) is configured as the spring (40) associated with thegroove (9).
 5. The control unit as recited in claim 1, wherein the cover(4) is capable of being joined with the frame (8) using laser welding(17), a snap-in connection (41, 42), a shaped spring device (18) or thelike.
 6. The control unit as recited in claim 1, wherein the base plate(11) is made of a material with good thermal conductivity, e.g., metal.7. The control unit as recited in claim 1, wherein the conductive tracks(10) are configured as pressed-screen tracks or as flexible-foil tracks.8. A method for manufacturing a control unit (1) that is configuredaccording to claim 1, comprising the following steps: Press and/or bonda base plate (11) into a frame (8) that includes a recess (9) acrosswhich electrical conductive tracks (10) extend to supply electricalpower; Bond a circuit carrier (12) designed to retain electroniccomponents (13) to the base plate (11); Establish contact between thecircuit carrier (12) and the electrical conductive tracks (10) using abonding method, for example; Pour a sealing gel (16) into the recess (9)provided in the frame (8), whereby the sealing gel (16) has a viscositysuch that it can flow around the conductive tracks (10) that extendacross the recess (9); Insert a cover (4) configured with a shapedsection (40) into the recess (9)—filled with the sealing gel (16)—of theframe (8) to hermetically seal the control unit (1), and Apply apredetermined amount force to the cover (4) to create hydrostaticpressure in the sealing gel (16).
 9. The method as recited in claim 8,wherein the base plate (11) is formed of metal and is mounted on acooling surface (19), the base plate being in contact with the coolingsurface.
 10. The method as recited in claim 8, wherein the control unit(1) is acted upon with a predetermined amount force using a springdevice (20).